Members will vote on a final set of motions, including financial plans for a merged association, at two extraordinary general meetings (EGMs).
Eventia chairman Simon Hughes and IVCA chief executive Marco Forgione told C&IT that the EGMs would be held at the end of November or beginning of December.
"We need to operate in a more strategic way, as we have been through a substantial period of change in how clients are commissioning," said Forgione. "However, we cannot assume a vote will go one way or another."
If the separate meetings result in a positive vote from members, a final, joint EGM will be held in the new year.
Hughes said: "We need to get the right membership fees, but our intention is not to look at this as a way of increasing fee levels."